First of all, do not get me wrong, SE has an awesome star/planetary system generator which can cause a lot of wonders a lot of times, and for me, it has caused a lot of "wow" moments, but we must all admit it- the software is still in Beta, and the generator is fit for improvement.

Now, just to say ahead, none of these suggestions will be some sort of huge game changing features, but rather many smaller features that would pile up and create a better generation system together.

So, here they are:

1. Comets with hyperbolic orbits- These are the fresh comets from the Oort cloud of a system that have extremely elongated orbits. At perihelion they are extremely close to the star. Due to their extremely elongated orbit, they get completely flung back into the Oort cloud. Due to this, they have extremely long orbits (hundreds of thousands, if not millions of years) and most of the time do not even come back a second time. These would have an orbital time of infinity, and would despawn once they finish their orbit. From time to time, these comets would randomly spawn at the edges of the star system and have a no-return orbit generated. An example of this would be PANSTARRS and ISON in our Sol system (go and have a look at them in SE and you will see exactly what I am thinking about). Also, the age of these comets should probably be much lower than the star system itself. I think each system should be limited to having around 2 of these at one time.

2. Planets around white dwarfs- I am not sure if I am missing something here (would something like this be impossible for some reason in real life, or is it actually already in the game), but to me it is kind of weird how (rarely) solitary neutron stars, and even black holes can have planets around them, but I have never encountered a white dwarf with a single planet. Is there some scientific reason why this is impossible? Because it would be cool if we could have this. So, first there would be an area around the star where no planets could generate(the size of the giant and the area around it at which the gravity would tear a planet apart). Then there would be a second area around the star, in which planets could generate, but these would be ruined worlds that, despite managing to survive the death of the star, still did not make it out in one piece. They would be dwarf planets inside of asteroid belts of their own debris, and could be quite oblate, without an atmosphere since it would have been blown off by the red giant. The final area around the star would let normal planets be generated.

3. Extremely oblate planets very close to their star- Planets within a certain area of the star, where the gravity of the star becomes so strong, would be oblate depending on the strength of the gravity. This would occur most frequently around red giants, but nothing prevents it from happening to planets in other systems as well.

4. There should be a logical categorization of gas giants and rocky planets in a system- What I mean is, it shouldnt be common for systems to have a bunch of rocky planets, and then in the middle of all of them is just a random gas giant. Although this wouldnt become impossible, it would be much rarer than before.

5. Gas giants with more moons- The current amount of moons any planet can have is caped at 13 (I THINK, but it is something like that). Although the reason is that a lot more procedural moons would slow down performance, it would make gas giants (which would usually have a lot of moons) much more interesting. I think that the cap should be raised to something around 25/30

6. Minimum distance of moons from a gas giant should be decreased- so far, I have never ran into a Metis-like object. For those who dont know, Metis is Jupiters closest moon- it is so close that it completes it orbit in around 7 hours. I have never even encountered anything even close to Metis. And Metis isnt even an anomaly- there a bunch of other moons around Jupiter that are very close. In the game, these moons should be asteroids (since any larger body would have been ripped apart and turned into a ring) inside of ring systems. They could be a reasonable distance away from the planet- enough that it doesnt rip it apart as well.

7. Categorization of moons- This would be especially useful for gas giants since they would have so many of them. Basically, moons would be split into different "groups". These groups would have the moons relatively close together and would be separated from other groups by a distance either negliable or relatively far away. Each of these groups would have some sort of traits associated with them- for example, one group could primarily be composed of asteroids with a large inclination and distance from the planets, while another would be a group with relatively large rocky moons orbiting a medium distance away from the planet. Every group would also have some variables depending on its distance from the planet- e.g. very distant groups would be composed out of asteroids with a high inclination, close ones composed of asteroids and have an extremely small inclination etc.

8. Very distant objects should have bigger inclinations- If you look at the map of the solar system, you will see that the outermost planets have a very large inclination due to the weak gravity in the region. Right now, such objects in SE are impossible to find, which makes the systems look a bit flat and seem less dynamic from the map view.

9. Rarer Titans- Right now, titans feel way too common. After all, there is only 1 Titan in our own system, but I can find an average of 3 titans in an average system. They should feel a bit more rare and special.

10. Retrogade orbiting/rotating moons/planets- Triton orbits retrogade, for example, and Venus rotates retrogade, so I do not see a reason why this should not be implemented as a rare anomaly.

Retrograde orbits for moons and retrograde rotation are both already in SE, and have been for a long time.

QuoteDeathStar ()

Rarer Titans

Why? The number of objects in our own system should not constrain what we find in others. There are types of planets known to exist that don't exist at all in our system, yet we don't just ignore them because of that. There is no reason that I know of that Titan-like worlds should be rare.

QuoteDeathStar ()

Categorization of moons

This already exists to some extent (outer moons of gas giants tend to be asteroidal and have more irregular orbits). As for the rest, this would probably not be very easy to implement, nor is it critical right now.

QuoteDeathStar ()

There should be a logical categorization of gas giants and rocky planets in a system

Why? Systems like this can exist, and systems with more massive and less massive planets interspersed are known. If you're going to make something rare, it should be because it is known to be rare or very likely to be rare.

QuoteDeathStar ()

Extremely oblate planets very close to their star

No. This would be very rare, and would only happen for very small stars. It is a lot more difficult for a star to cause a planet to be oblate than it is for a planet to cause a moon to be oblate. And anyway, this is already implemented; put a large, low density planet in a tight orbit around a star, and it will have a definitely non-zero oblateness value.

[Comets with hyperbolic orbits] I'm not sure if it'd really add much for most users, though from scientific perspective it would certainly be nice to allow for comets with e>1. Why would they have young ages though? Non-periodic and hyperbolic comets are of the same material that the star system formed from and should have the same ages.

White dwarf planetsThese do exist in nature, and hopefully will exist in Space Engine someday. Your intuition on their orbital ranges and properties is good, though you don't have to worry about tidal forces shattering them. Even as a star expands, the tidal force felt by an orbiting body does not change, and neither does the strength of the star's gravity. (Actually it gets weaker due to the star losing mass).

Edit: Correction: These have already been implemented.

Oblate planets You're actually thinking prolate, which is the stretching of a planet due to tidal forces (think the shape of an egg, or an American football). This is currently not implemented. Oblateness is the bulging of a planet along its equator due to its rotation, and this is already implemented.

Correction2: Actually both are implemented, but it is most apparent with prolate stars, such as in close/contact binary systems.

logical categorization of gas giants and rocky planets in a system We already know from exoplanet data that many systems do not have a neat and orderly distribution of planet types -- solar system evolution is very dynamic and chaotic. SE doesn't model solar system formation processes but I think it does currently do an okay job at producing realistic-looking systems.

Gas giants with more moons Certainly. I think the cap right now exists for engine limitation reasons -- SE can only readily simulate a certain number of bodies per star system, but hopefully in the future it will be able to handle more.

Minimum distance of moons from a gas giant should be decreased Yes, this basically gets into a better treatment of Roche limits for planets. I think SE does consider the Roche limit currently, but it's not a perfect thing and depends on composition of the body.

Categorization of moons I agree with HarbingerDawn here. SE already does a little bit of this, though there can certainly be improvements in the future.

Very distant objects should have bigger inclinations Basically SE should simulate Kuiper Belts / Scattered Disk objects. Good suggestion and I hope this is implemented as well.

Rarer Titans What HarbingerDawn said. Titan-like bodies (worlds with surfaces that support liquids other than water and at cold temperature) may actually be fairly common in the universe. I don't see any reason to make them more rare than they already are in SE.

Retrograde orbits/rotation Already implemented! If you see a planet with an axial tilt of between 90 and 270 degrees, it has retrograde rotation. There are also retrograde-orbiting moons.

Non-periodic and hyperbolic comets are of the same material that the star system formed from and should have the same ages.

Actually, hyperbolic comets could be even older than the stuff in the system they happen to dive into. Or younger. It's theorized that there's plenty of interstellar chunks of dirty ice out there. Ejections are a common result of gravitational interactions.

QuoteWatsisname ()

Actually both are implemented, but it is most apparent with prolate stars, such as in close/contact binary systems.

Oh? And how would one make a prolate object? Using a negative value in oblateness?

QuoteWatsisname ()

I think the cap right now exists for engine limitation reasons -- SE can only readily simulate a certain number of bodies per star system, but hopefully in the future it will be able to handle more.

Hm... and what would that certain number be? Some of my systems have a couple of hundreds of objects rolling around, and I haven't noticed any unusual problems in them... unless stars shining through asteroids can be caused by that.

QuoteWatsisname ()

Categorization of moons I agree with HarbingerDawn here. SE already does a little bit of this, though there can certainly be improvements in the future.

Personally, I'm pretty skeptical about any kind of categorization of moons that tries to pack them neatly and universally. Just like planets were when exoplanetary systems became known, moons will, more likely than not, be found to not follow any specific pattern, other than a separation between those formed with their primaries, those captured later from interplanetary space and asteroid-like collisional families. Other than that, chaos should reign supreme.

Oops, you're right. I was remembering the reflection effect in close binaries and thought that the tidal distortion was shown as well. But they're just oblate spheroids.

QuoteJCandeias ()

Actually, hyperbolic comets could be even older than the stuff in the system they happen to dive into. Or younger. It's theorized that there's plenty of interstellar chunks of dirty ice out there. Ejections are a common result of gravitational interactions.

Absolutely, and there are a very large number of rogue planets out there as well. The consensus view though is that non-periodic and hyperbolic comets formed with the system, and gravitational interaction with nearby passing stars send them in on such orbits. There was a paper a little while ago that claims many of the comets are actually captured from other stars in the sun's stellar nursery, but even if this is true the material will be roughly of the same age.

QuoteJCandeias ()

Hm... and what would that certain number be? Some of my systems have a couple of hundreds of objects rolling around, and I haven't noticed any unusual problems in them... unless stars shining through asteroids can be caused by that.

I don't recall offhand, but SpaceEngineer talked about it in a thread somewhere.

Quote

Personally, I'm pretty skeptical about any kind of categorization of moons that tries to pack them neatly and universally. Just like planets were when exoplanetary systems became known, moons will, more likely than not, be found to not follow any specific pattern, other than a separation between those formed with their primaries, those captured later from interplanetary space and asteroid-like collisional families. Other than that, chaos should reign supreme.

Chaos is definitely important and there is no pattern that can be applied universally, though there are some patterns that arise from dynamical and tidal effects. For example it is no coincidence that Io is a hot volcanic world, Europa has a liquid ocean, and Ganymede/Callisto are rock/ice moons. But we can't say that the same number and types of moons would exist around all Jupiter-like planets; each satellite system is going to be unique.

QuoteHarbingerDawn ()

No, it would just be a triaxial ellipsoid, with each axis having a different radius value. This was implemented in Celestia.

Hyperbolic comets are already supported. You may define them in catalog using Eccentricity >1 and PericenterDist instead of SemimajorAxis and GravParam instead of Period (read in Wikipedia if you don't know what is this). However comets will glitch in interdtellar space (disappear if sun goes out of screen), have limited length of orbital path drawn and of course they will not be affected by other stars (illumination and gravity). Anyway at distance greater than 2-3 ly comet must be switched to next planetay system, but this is too hard to implement and not necessary at this stage.

Regarding other suggestions, I agree with Harb and guys.

And for close and contact binary stars, their shape must be not even 3-axial ellipsoid, but Roche zone shape, that is I think impossible to combine with Bruneton's atmosphere code. So I must implement my own atmosohere code for stars first.

Additional moons for gas giants is simple, our Solar System handles all list of known moons (few hundreds). So I will add them eventually.

Absolutely, and there are a very large number of rogue planets out there as well. smile The consensus view though is that non-periodic and hyperbolic comets formed with the system, and gravitational interaction with nearby passing stars send them in on such orbits. There was a paper a little while ago that claims many of the comets are actually captured from other stars in the sun's stellar nursery, but even if this is true the material will be roughly of the same age.

Yeah, but even if that is absolutely true (and, being the study of the Oort cloud so theoretical for the time being, it may well end up not being quite so), you can have comets, especially those in hyperbolic orbits, that come from interstellar space, not from any system's Oort cloud. That was my point. You shouldn't restrict comet ages in any way because you can, in fact, have comets of any age entering your system. Even if the vast majority is part of the system since the beginning, and therefore of the same age.

QuoteWatsisname ()

there are some patterns that arise from dynamical and tidal effects. For example it is no coincidence that Io is a hot volcanic world, Europa has a liquid ocean, and Ganymede/Callisto are rock/ice moons.

Certainly, but I don't think that's what DeathStar was referring to. I think he was thinking more in terms of "OK, this is the zone of big moons, small moons go there, here should be the inclined ones, there those with retrograde motion", etc. As if there were general and universal rules that determine those things. I don't think there are. Not in any way clear-cut or deterministic, at least.

QuoteWatsisname ()

But we can't say that the same number and types of moons would exist around all Jupiter-like planets; each satellite system is going to be unique.

Agreed, except that I wouldn't restrict this idea to jovian or neptunian worlds. If you put an Earth where Neptune is, it could have (in fact, I think it would be very likely to have, since its sphere of influence would be much, much wider) its own extensive family of moons instead of our single celestial companion.

Regarding the rest, again, please don't take the Solar System as a model for everything

You are right about this. However since 1. Evolution of solar systems can not be simulated at the moment and 2. Since we don't know how other star systems look like we are left with no other option other than to apply our solar system model to any other star system that the procedural engine generates with a similar structure to ours. What I mean is that only similar star systems should have these properties I described before i.e. systems with a few terrestrial planets at their inner orbits, an asteroid belt after that, a few gas and ice giants on the outer orbits and a couple of frozen worlds, titans either in between or at the most distant orbits e.g pluto- type objects. Any deviation from this should force the engine to randomize things or use a different algorithm which of course may only be partially correct from a scientific point of view. In any case there are probably many mathematical simulations/models out in the scientific community that can be applied to systems with completely different structure from ours. Wether these models can be applied to space engine procedural mechanisms or not, only Space Engineer can comment on that.

QuoteJCandeias ()

We shouldn't limit ourselves to what's known. We should limit ourselves to what's possible. Granted, this is more a matter of phylosophy than anything else, but I truly believe that within the vastness of the Cosmos just about anything that is possible will exist somewhere.

QuoteSpaceEngineer ()

Anyway, I should note: as long as SE is a scientifically accurate Universe simulator, then one day it will implement ALL space objects and phenomenon that are known to modern astronomy. So you may not bother yourself with questions like "will SE one day have meteor rain implemented". I guarantee that it WILL.

So don't worry. The Master knows, The Master Listens, The Master will Provide

Added (12.11.2013, 00:46) --------------------------------------------- Guys may I suggest to continue this very interesting discussion in this thread? Lets leave the work progress thread for Space Engineer's comments and small comments from us..

I think you are both right and both wrong at the same time. JCandeias, your idea is sound as long as it is appled to procedural only systems with a probability coefficient. HarbingerDawn, DeathStar, you are also correct. Mathematical theories should be backed-up by observation and experimental verification. Catalog systems and procedural system with similar structure to our solar system should use the solar system model.

Yeah, but even if that is absolutely true (and, being the study of the Oort cloud so theoretical for the time being, it may well end up not being quite so), you can have comets, especially those in hyperbolic orbits, that come from interstellar space, not from any system's Oort cloud. That was my point. You shouldn't restrict comet ages in any way because you can, in fact, have comets of any age entering your system. Even if the vast majority is part of the system since the beginning, and therefore of the same age.

I agree with you and Watsisname about this- it was my own mistake to count all of the comets younger than the system, and I agree that they could be of any age really.

QuoteJCandeias ()

Certainly, but I don't think that's what DeathStar was referring to. I think he was thinking more in terms of "OK, this is the zone of big moons, small moons go there, here should be the inclined ones, there those with retrograde motion", etc. As if there were general and universal rules that determine those things. I don't think there are. Not in any way clear-cut or deterministic, at least.

I do not understand why you say that I was referring to what you said rather than what Watsisname said. I was referring to both things. Because, let's face it, you won't be finding a moon with a near-circular, near 0 inclination orbit at extreme distances from the parent body, since:

1. Most bigger, 'regular' moons get formed at a medium distance away from the parent body- in a region where the accretion disc doesn't get attracted into the actual parent planet, but at the same time is dense enough to form larger objects. If the moon got catapulted into a very far-out orbit, then it certainly wouldn't have the circular orbit it used to, rather an irregular one.

2. If the moon was captured, then there is nearly no chance for it to actually form a circular orbit- that is why Triton has an irregular orbit.

Outer moons would be captured asteroids, captured planetoids or ejected regular moons. They would have some chance to have a fairly large sized objects, but this would mostly be uncommon

Inner moons would never be able to become huge-tidal forces would really just tear apart anything that was even starting to circularize